added bootstrap

js/theme.js

@@ -0,0 +1,21 @@
+const dark_theme = document.querySelector("#dark_theme");
+
+dark_theme.addEventListener("click", () => {
+  if (dark_theme.checked) {
+    document.documentElement.setAttribute("data-bs-theme", "dark");
+    localStorage.setItem("data-bs-theme", "dark");
+  } else {
+    document.documentElement.setAttribute("data-bs-theme", "light");
+    localStorage.setItem("data-bs-theme", "light");
+  }
+});
+
+document.addEventListener("DOMContentLoaded", () => {
+  var theme = localStorage.getItem("data-bs-theme");
+  if (theme) {
+    document.documentElement.setAttribute("data-bs-theme", theme);
+    if (theme === "dark") {
+      dark_theme.checked = true;
+    }
+  }
+});